The present invention relates generally to cartridges for data information disks. The invention relates more particularly to cartridges for protecting rewritable optical disks used for mass storage of alphanumeric data which may be accessed by a computer. Such a disk is preferably enclosed within a cartridge to prevent the disk from being scratched or nicked during handling. In use, the cartridge containing the disk is inserted into a disk drive having an optical reader/writer and thereafter a sliding door on the cartridge is opened to expose portions of the disk to the reader/writer.
A cartridge of this general type is disclosed in Sandell et al U.S. Pat. No. 4,908,817. The cartridge of that patent comprises a pair of interlocking shells which define a compartment containing the disk. The sliding door is generally U-shaped and is formed in part by a pair of shutters which normally close access apertures formed in opposite sides of the cartridge. When the door is slid open, the shutters open the access apertures. Upon opening of the apertures, one side of the disk is exposed to a rotary drive spindle of the disk drive and to a laser for reading and writing data on the disk. The other side of the disk is exposed to a magnetic head for erasing data from the disk.
The Sandell et al cartridge is disadvantageous in that, for all practical purposes, the disk becomes a permanent part of the cartridge and cannot be easily removed from the cartridge and replaced with another disk. The shutters also commonly are made of metal, which is susceptible to scratching and necessitates costly stamping and cleaning during manufacture. Suzuki et al U.S. Pat. No. 4,746,013 discloses a cartridge with a hinged cover which may be opened to permit removal and replacement of a compact disc. That cartridge, however, is adapted for use only with a read-only memory (ROM) compact disc and cannot be used with an erasable or rewritable optical disk since the hinged cover does not include a shuttered aperture capable of providing access to an erasing head.
When the disk contains alphanumeric data, it is necessary that the disk rotate precisely about a predetermined axis in order to maintain a precise relationship between the disk and the read/write laser. In the cartridge of the Sandell et al patent, apertured metal hubs are glued to opposite sides of the disk and coact with the spindle and the magnetic pulley assembly of the disk drive to cause the disk to rotate precisely and concentrically about the axis of the spindle with virtually no run-out. It is tedious, time-consuming and expensive, however, to affix the hubs to the disk. Moreover, the hubs must be assembled to the disk with great positional accuracy and, in many cases, this is not achieved in mass assembly procedures and thus a relatively large number of disks must be scrapped.